Tutorial by Examples: b

Common instances of Bifunctor

Two-element tuples (,) is an example of a type that has a Bifunctor instance. instance Bifunctor (,) where bimap f g (x, y) = (f x, g y) bimap takes a pair of functions and applies them to the tuple's respective components. bimap (+ 2) (++ "nie") (3, "john") --> (5,...

Haskell Language • Bifunctor

Basic LocalDates

A given year-month-day: LocalDate oneJanuaryNineteenSixty = new LocalDate(1960,1,1); Today's date: LocalDate today = LocalDate.now() Tomorrow: LocalDate tomorrow = LocalDate.now().plusDays(1); Yesterday: LocalDate yesterday = LocalDate.now().minusDays(1); Two weeks ago: LocalDate tw...

jodatime • LocalDate (dealing with dates)

Basic Example of Html 5 cache

this is our index.html file <!DOCTYPE html> <html manifest="index.appcache"> <body> <p>Content</p> </body> </html> then we will create index.appcache file with below codes CACHE MANIFEST index.html write those files that you want ...

HTML • HTML 5 Cache

Definition of Bifunctor

Bifunctor is the class of types with two type parameters (f :: * -> * -> *), both of which can be covariantly mapped over simultaneously. class Bifunctor f where bimap :: (a -> c) -> (b -> d) -> f a b -> f c d bimap can be thought of as applying a pair of fmap operation...

Haskell Language • Bifunctor

Using ArrayObject Iterator

Php arrayiterator allows you to modify and unset the values while iterating over arrays and objects. Example: $array = ['1' => 'apple', '2' => 'banana', '3' => 'cherry']; $arrayObject = new ArrayObject($array); $iterator = $arrayObject->getIterator(); for($iterator; $iterator-...

PHP • Array iteration

Declaring sub-namespaces

To declare a single namespace with hierarchy use following example: namespace MyProject\Sub\Level; const CONNECT_OK = 1; class Connection { /* ... */ } function connect() { /* ... */ } The above example creates: constant MyProject\Sub\Level\CONNECT_OK class MyProject\Sub\Level\Connection...

PHP • Namespaces

Sample illustration using ASP.Net Web Forms

GridView definition on ASPX page As shown below, first column of grid is defined as a checkbox column, which is conditionally cleared as shown in further examples below (the header checkbox is only for selecting/un-selecting all rows on current page, but same can be extended for all on grid easily)...

devexpress • Implementing conditional selection of Grid rows in DevExpress GridView

Basic CRUD Operation

MongoDB stores data records as BSON documents. BSON is the binary representation of JSON. $ python >>> from pymongo import MongoClient >>> client = MongoClient() >>> col = client.mydb.test Create Insert a single document insert_one(document) >>> result = ...

PyMongo • Getting started with PyMongo

Default values of uninitialized variables

Although not necessary in PHP however it is a very good practice to initialize variables. Uninitialized variables have a default value of their type depending on the context in which they are used: Unset AND unreferenced var_dump($unset_var); // outputs NULL Boolean echo($unset_bool ? "tr...

PHP • Variables

Sample Job

class UserUnsubscribeJob < ApplicationJob queue_as :default def perform(user) # this will happen later user.unsubscribe end end

Ruby on Rails • Active Jobs

ssh_exchange_identification: read: Connection reset by peer

This error message may be produced by the OpenSSH ssh client. It means that the TCP connection between the client and the server was abnormally closed by the server immediately after being accepted. Common reasons for this message include: The SSH server process is malfunctioning--for example, it...

Secure Shell • Debugging ssh problems

ssh_exchange_identification: Connection closed by remote host

This error message may be produced by the OpenSSH ssh client. It means that the TCP connection between the client and the server was closed by the server immediately after being accepted. This message generally indicates the SSH server has been configured not to accept connections from the client fo...

Secure Shell • Debugging ssh problems

Creating an Active Job via the generator

$ rails g job user_unsubscribe

Ruby on Rails • Active Jobs

Observer Mock

class ObserverMock implements Observer<any> { closed?: boolean = false; // inherited from Observer nextVal: any = ''; // variable I made up constructor() {} next = (value: any): void => { this.nextVal = value; }; error = (err: any): void => { console.error(err); }; ...

Angular 2 • Mocking @ngrx/Store

Smart way to setting up the base_url

The following lines of code is more smart way to setting up the base_url in codeigniter: $config['base_url'] = ((isset($_SERVER['HTTPS']) && $_SERVER['HTTPS'] == "on") ? "https" : "http"); $config['base_url'] .= "://".$_SERVER['HTTP_HOST']; $config[...

codeigniter • Base url in Codeigniter

Build a classifier

# imports import weka.core.converters.ConverterUtils.DataSource as DS import weka.classifiers.trees.J48 as J48 import os # load data data = DS.read(os.environ.get("MOOC_DATA") + os.sep + "anneal.arff") data.setClassIndex(data.numAttributes() - 1) # configure classifier...

weka • Getting Started With Jython in Weka

Cross-validate Classifier Error Bubble

# Note: install jfreechartOffscreenRenderer package as well for JFreeChart library # imports import weka.classifiers.Evaluation as Evaluation import weka.classifiers.functions.LinearRegression as LinearRegression import weka.core.converters.ConverterUtils.DataSource as DS import java.util.Ran...

weka • Getting Started With Jython in Weka

Thread-local Objects

A thread-local object gets initialized on its first use in a thread. And as the name suggests, each thread will get a fresh copy independent of other threads. use std::cell::RefCell; use std::thread; thread_local! { static FOO: RefCell<f32> = RefCell::new(1.0); } // When this mac...

Rust • Globals

Remove / Add delimiter between words

Remove delimiter The function humanize($words), takes multiple words separated by underscores and adds spaces for underscores with capitalized each word. echo humanize('mac_donald'); // Prints 'Mac Donald' The function can also replace any declared separator/delimiter. In this case, delimiter w...

codeigniter • Play with English word with INFLECTOR helper

Basic Navigation Commands

Change Directory Navigate to a directory cd [directory] Example: Changing to the projects directory username$ cd projects Navigate to the root directory (regardless of working directory) cd / Navigate to the parent directory (the directory containing the working directory) cd .. ...

terminal • Terminal Navigation